pueyes



D. PURVES.

BOILBR PLUB.

(No Model.)

No. 372,487. Patented Nov. 1, 1887.

WITNESYSES i INVENTOR: gifle ATT() YS.

UNITE STATES AthrnNT OFFICE.

DAVID PURVES, OF FERRO DENE, GREEN LANE, NORTH DULVIOI-I, COUNTY OFSURREY, ENGLAND.

BOlLER-FLU E.

SPECIFICATION forming part of Letters Patent No. 372,487, dated November1, 1887.

Application filed Oct. ber 23, 1SSG. Serial No. 217,033.

To all whom it' may] concern,.-

Be it known that I DIvID PUitvEs, of Ferro Dene, Green Lane, NorthDulwich, county of Surrey, England, have'invented a new and useA 5 fnlImprovement in Boiler-Flues, (for which I .have obtained a patent inEngland, March 23, 1885, No. 3,722,) of which the following is aspecification, reference being had to the annexed drawings, lforming apart thereof, in

1o which- Figure l is a transverse section of a portion of aboiler-sheet, taken on line a: .t in Fig. 3. Fig. 2 is a transversesection of a portion of a boiler-sheet, taken on line x in Fig. 3, and

Fig. 3 is a transverse section of a boilerflue, showing the projectionof the circumferential ribs.

Similar letters of reference indicate corresponding parts in all theviews.

The object of my invention is to provide a boiler-flue havingstrengthening` ribs formed integrally with the plates Yfor strengtheningthe tlues, to enable them to better withstand the steampressnre, but soconstructed as to give that required strength without the formation ofcavities likely to gather injurious dcposits of scale, and without thecircumferential seams which are required when a ilne is formed of aseries of ilangcd hoops or is st-iff- 3o ened by separate channeledhoops.

The invention consists of a boiler ilue provided with a band or ribformed integrally therewith and in forming such rib upon the plate,substantially as hereinafter set forth.

In carrying ont my invention I roll in each plate of which the flue isformed ribs B, which project beyond the general plane of the plate, uponone side thereof, the plate bei ng concaved more fully (No model.)Patented in England March 23, 1885, No. 3,722.

or channeled in the other side directly oppo- 4o site the rib, and Imake the rib radially thicker than the body of the plate. On section theribs are, when finished, as shown by A in Fig.

l or I; in Fig. 2, at such distances apart as the strength required willadmit. Between the ribs the flue is a plain cylinder. After the platesare bent into the required curved form, the adjoining ends of the platesare secured together by welding or riveting. The plates are preferablybent with the ribs on the concave surface. Ihe thickened bands for theribs are made on theplate before the plate is bentinto cylindrical form;but the rolling of these thickened bands into ribs may be performedeither before the plate is bent or after it is bent. Vhen the ends ofthe platesarejoined by riveting, the ribs will be finished before theplates are bent.

Having lhnsfully described inyjiivention,

I claim as new and desire to secure by Letters 5o Patentl. In themanufacture of boiler llues, the herein-described method of making thesame, which consists in forming the plate with thickcned bands on oneside and channeling it on o5 the opposite side, and then rolling thethickened bands into stifiened ribs, with the channel intact,substantially as set forth.

2. A boilerflue formed of a plate having cir cumferential channeledstiffening-ribs formed 7o upon the plate by rolling without intermediatecircumferential seams, substantially as described.

DAVID PURVES.

Vitnesses:

ROBERT H. I. CoMERFoRD, Aue. SrioiiUDE.

